What is carbon monoxide poisoning?

Carbon monoxide (CO) is a colorless, odorless gas that comes from burning fuels such as natural gas, gasoline, oil, kerosene, wood, or charcoal. Carbon monoxide poisoning means that you breathe in too much CO instead of oxygen. Without oxygen, your body tissues are damaged and you could die.

What is the cause?

Levels of CO can build up to dangerous levels in a short time if:

A gas appliance, such as a stove, furnace, water heater, or generator, is not working right or is not used correctly.

Fuel is being burned in an area that is not well ventilated, such as using a gas or kerosene heater in the home or leaving a car running in a garage with the garage door closed.

You ride in the back of a pickup truck that has a camper shell, or if you swim behind a motorboat or spend time next to a boat with the engine running.

What are the symptoms?

Symptoms may include:

Headache

Nausea

Blurry or double vision

Feeling like you cannot get enough air

Dizziness

Confusion

Fainting

Because you cannot see or smell CO, you may not know that CO poisoning is causing your symptoms. Symptoms of CO poisoning can be mistaken for flu or food poisoning. One way to check this is to leave your house and see if your symptoms get better. If they come back when you go back home, you should suspect CO poisoning. Also suspect carbon monoxide if others in your household start having these symptoms at about the same time.

If you are sleeping when the CO levels get too high, you may die before you ever wake up and notice any symptoms. Babies, older adults, and people with anemia, heart, or lung disease are very sensitive to high levels of CO. It is important to have carbon monoxide detectors in your home that alert you to dangerous CO levels.

How is it diagnosed?

Your healthcare provider will ask about your symptoms and medical history and examine you. You will have a blood test for CO poisoning.

How is it treated?

If you have symptoms that you think could be caused by CO poisoning:

Get fresh air right away. Get people and pets out of the building or vehicle.

Call 911 or have someone take you to an emergency room and tell them you think you might have CO poisoning. CO poisoning can be diagnosed with a blood test if the test is done soon after exposure to CO.

You will be given oxygen to treat CO poisoning.

How can I help care for myself?

If you have been treated for CO poisoning:

Get plenty of fresh air afterwards.

If you were in your home when you got sick, you need to have your furnace and any gas appliances checked by a professional before you go back to your home.

Follow your healthcare provider's instructions. Ask your provider:

How and when you will hear your test results

How long it will take to recover

If there are activities you should avoid and when you can return to your normal activities

How to take care of yourself at home

What symptoms or problems you should watch for and what to do if you have them

Make sure you know when you should come back for a checkup. Keep all appointments for provider visits or tests.

How can I prevent carbon monoxide poisoning?

To prevent a buildup of CO in your home and car:

Have fuel-burning appliances such as oil and gas furnaces, gas water heaters, gas ranges and ovens, gas dryers, gas or kerosene space heaters, fireplaces, and wood stoves installed by a professional. Make sure they vent to the outside. Have them inspected by a qualified service technician at the start of every heating season and repair any defects. Make sure that the flues and chimneys are connected, in good condition, and not blocked.

Maintain all appliances according to the manufacturers' instructions.

When you use a gas or kerosene heater, always have a window or door open to let fresh air in. Don't sleep in any room or space with an unvented gas or kerosene space heater.

Never leave the car running in a garage, even if the garage door to the outside is open. Fumes can build up very quickly in the garage. Fumes will also build up in the living area of your home if the garage is attached, even if the door between the house and garage is closed.

Keep the exhaust system of your car in good repair.

Never use a gas range or oven to heat your home, even for a short time.

Never use a charcoal or gas grill indoors, not even in a fireplace.

Don't use any gas-powered engine, such as a mower, weed trimmer, snow blower, chain saw, small engine, or generator, in an enclosed space.

Put CO detectors on each floor of your home and in each bedroom. They will sound an alarm if the CO level in your home is too high. Check or replace the battery when you change the time on your clocks each spring and fall.

Don't ignore symptoms, particularly if more than 1 person is having them. You could pass out and die if you do nothing.

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.